This invention relates broadly to optical-fiber systems for measuring temperature and, more particularly, to methods and systems for determining the most extreme temperature prevailing along the length of an optical-fiber light guide.
It is well known that the temperature of high-voltage electrical equipment may be determined remotely by means of a monitoring system which responds to temperature-induced changes in the light-propagation or loss characteristics of an optical fiber of the kind comprising a core, a core cladding, and a jacket for the cladding. Several such systems are proposed or referenced in the following publication: ISA Transactions, Vol. 19, No. 4, pp. 55-62. Those systems and other known temperature-monitoring systems of the optical-fiber type are suitable for determining the average temperature along the length of the fiber. They are, however, unable to discriminate between small temperature change affecting a long length of the fiber and a large temperature change affecting a short length thereof. Thus, they are unsuitable for certain applications--such as determining the maximum temperature prevailing along the length of a fiber deployed within a high-voltage transformer or within a tunnel containing high-voltage electrical cable.